Apparatus for forming rigid web-reinforced composites

ABSTRACT

Apparatus for forming rigid web-reinforced extruded composites in which a pair of webs are fed through an extrusion die in spaced parallel relationship, the die being shaped to form two extrusions joined in mirror image relationship and wherein the extrusions are pulled through a curing station and past a slitter knife by driving the reinforcing webs. The slit extrusions can then be cut to length. Useful applications include windshield wiper blades and seals.

O a 3] m I. m 3 1 mien aiaies Pawn? 1191 1 1 9 3 Skohei 1 11113 M, W73

[ APPARATUS FOR FORMING RIGID 3,477,126 11/1969 Price 425/114 )4WEBJEKNFORCED COMPOSITES 3,555,127 1/1971 Messer et 264/40 3,557,40311/1971 Lernelson 425/142 X Inventor: Max beLEd1son, NJ. 3,646,8943/1972 Hasten et a1 425/315 x [73} Assignee: Dow Corning Corporation,Midland, Pn-mmy Examiner j Spencer Overholser M AssistantExamiizerRichard Bernard Lazarus {22] Filed Jan 20 1972 Attorney- RobertF. Fleming, Jr., Howard W.

Hermann et a1. 21 Appl. No.: 219,427

[57] ABSTRACT 52 us. 01 425 114, 264 40, 264/149, Apparatus for f0"mugrigid webrreinforced extruded 264/174, 425,142 composites in which apair of webs are fed through an 51 11:1.(11 8291 3/10 extrusion die inSpaced Parallel wlationship, the die [58] Field of Search 425/114, 142,314, being Shaped form two extrusions Joined in mirror 42512 9 113; 24/40 14 149 74; 3 371 image relationship and wherein the extrusions arepulled through a curing station and past a slitter knife {56] Referencescu by driving the reinforcing webs. The slit extrusions can UNITEDSTATES PATENTS then be cut to length. Useful applications includewindshield wiper blades and seals. 2,826,782 3/1958 Dugall et a1.425/114 X 3,433,858 3/1969 Bauer et a1. 425 114 x 4 (31mm, 5 DrawingFigures 3,459,851 8/1969 MacPherson 4251114 X EXTRUDER l fi /2O 18 27EXTRUDER CURING CAPSTANS 5 AND GUlLLOTlNE DIE STATION SUTTER Z 14 LflIPatented July 10, 1973 2 Sheets-Sheet l mZED IEw Patented Jul 10, 1973 2Sheets-Sheet P AFFARATUS FOR FORMING RIGID WEB-REINFORCED COMPOSITESBACKGROUND OF THE INVENTION The present invention relates to apparatusfor forming rigid web-reinforced extruded composites and, moreparticularly, also relates to a method of vehicle windshield wiperblades using such apparatus.

Motor vehicle windshield wiper blades can be characterized as comprisinga generally triangular crosssection elongated strip of elastomericmaterial to which is affixed a metallic reinforcing strip which urgesthe elastomeric material into contact with a vehicle windshield andwhich also serves as attachment means for attaching the wiper blade tothe wiper arm. In the manufacture of wiper blades it is a commonpractice to mold the elastomeric material in mirror image back-tobackrelationship; i.e., with the wiping edges at opposite sides of themolded configuration. The mold is shaped to produce suitable notches inthe finished product for attachment of the metallic backing strip to theconfiguration. The molded configuration after removal from the mold issplit to provide two separate blades and the wiping edges are trimmed toremove flash and provide a smooth wiping edge. The molded elastomericparts are then attached to the metallic backing strips providing afinished blade suitable for mounting on the vehicle wiper arm. Ofnecessity, this prior art method, while producing satisfactory results,introduces a number of handling steps which results in substantial costto the operation. Additionally, a certain amount of material isnecessarily wasted in the trimming operation.

SUMMARY OF THE PRESENT INVENTION It is therefore an object of thepresent invention to provide a method of making windshield wiper bladeswhich is more efficient than those known heretofore.

in accordance with this and other objects, there is provided by thepresent invention apparatus for forming windshield wiper blades by meansof extrusion. The apparatus described hereinafter virtually automatesthe production of vehicle windshield wiper blades and is also readilyadaptable to the manufacture of other shaped elastomer composites suchas metal backed door seals, for example. In accordance with the presentinvention a pair of rigid reinforcing webs are passed in parallel spacedrelationship through an extruder die in which an uncured elastomericmaterial is extruded onto the strips in a desired configuration. Forwindshield wiper blades the die conforms in shape to a pair of wiperblades joined in mirror image relationship at their wiping edges,instead of back to back as in the prior art. The extruded composite ispulled through a curing station, which in the case of heat vulcanizingrubber may be simply a hot air oven, by means of a capstan which drivesthe two parallel supporting webs. The composite is then slit at itscenter providing a pair of elongated composites, each being a singlewindshield wiper blade or seal in cross-sectional configuration. Theslit composite can then be cut to desired length or, alternatively,rolled until ready for use.

The use of an extruder eliminates the multiple steps present in theprior art and also eliminates waste in that only a single slittingoperation is required. There is no need for trimming of flash from theextrusion and in the case of windshield wiper blades a clean wiping edgeresults directly from the slitting operation.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of thepresent invention will become obvious to those skilled in the art from areading of the following detailed description when read in connectionwith the accompanying drawings wherein:

FIG. 1 is a diagrammatic overall view of apparatus according to apreferred embodiment of the present invention;

FIG. 2 is a cross-section of the extruder die of the apparatus takenthrough the plane II-II of FIG. I with the reinforcing webs in place inthe die;

FIG. 3 is a side-view, partially diagrammatic, of the capstan system ofthe apparatus of FIG. ll;

FIG. 4 is a partial cross-sectional view through the apparatus of FIG. 1showing an endview of the capstans; and

FIG. 5 is a view in perspective of a finished windshield wiper blademade in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawingswherein like reference characters designate like or corresponding partsthroughout the figures thereof, there is shown in FIG. I a pair of websupply means 11 and 12 for feeding a pair of webs l3 and 14 into anextruder die l6 fed by an extruder 17. In the extruder die 16 an uncuredelastomeric material is extruded onto the webs l3 and H4 in the desiredconfiguration as shown by the crosssection in FIG. 2. The webs l3 and 14are preferably perforated to allow strike-through of the material andextrusion onto both sides of the web thereby thoroughly embedding thewebs in the extruded material. It is to be understood, however, that ifsufficient adhesion is obtained by the use of suitable priming agents orby the nature of the materials used, the use of the perforated web isnot an absolute necessity.

As may be seen from FIG. 2 the shape of the extruder die conforms inshape to a pair of windshield wiper blades having their wiping edgesjoined to form a mirror image relationship to each other. The exactconfiguration of the blades is a matter of design from the functionalstandpoint and it is to be understood that the shape shown is merely forillustrative purposes.

The extruded composite after leaving the die 16 is pulled through acuring station 20 by a capstan and slitter system 18. In the case ofheat-vulcanizable materials the curing station may besimply a hot airoven having suitable guide rollers conforming to the webs placedtherein, with the oven length and operating temperatures dependent uponthe specific materials being extruded. Such factors are well known tothose skilled in the art and heed not be described in detail herein.

Referring now specifically to FIGS. 3 and 4, the capstans are designedto drive the composite solely by use of the edges of the reinforcingwebs l3 and 114. Each of the rollers 19 has a pair of areas 21., 22 ofreduced diameter adapted to contact the peripheral edges of the strips13 and 4 to propel the same through the system. The rollers are drivenby means such as a motor 23 which drives the shaft of one of the rollersw on one side of the web and the shaft of one of the connecting wheels24 on the opposite side to provide the correct rotational direction forforward movement. While three drive rollers 19 are provided at each edgeof the composite as shown in FIG. 3, it is to be understood that thenumber shown is merely exemplary and any desired number may be provided.The drive means described for the rollers is also to be understood to beexemplary and not limiting.

Immediately adjacent the capstan is a slitter knife 26 held in place inthe center of the composite configuration for dividing the compositeinto its two elements in so far as cross-section is concerned. In thecase of windshield wiper blades it is possible to place cutting meanssuch as a guillotine 27 along the path of travel to periodically chopthe extruded composites into desired lengths, resulting in finishedblades. Notches 28 on the reinforcing strips 13, 14 may be utilized toautomatically activate the guillotine. The guillotine 27 may, however,be omitted and the resulting composite simply coiled until ready foruse.

As shown in FIG. 5, the finished windshield wiper blade includes theexposed edges of one of the backing webs 13 or 14 so that the device maybe readily affixed to a windshield wiper arm making use of the notches28 provided periodically along the length of the reinforcing web 13 or14. The cut edge 29 of the blade which edge was formed by the slitter 26is sufficiently smooth to provide a good wiping surface with no furthertrimming. No flash exists anywhere on the composite. The device is thusready for use as it leaves the apparatus.

It is to be understood that while the apparatus has been disclosedspecifically with reference to the manufacture of windshield wiperblades, it may be easily adapted to the production of various types ofrigid reinforced seals and other configurations simply by changing theextruder die and the capstan rollers. For example, door and window sealshaving metal backing strips may be made in this manner.

Various modifications and variations of the present invention willbecome obvious to those skilled in the art from a reading of theforegoing description. It is therefore, to be understood that within thescope of the appended claims the invention may be practiced as otherwisedescribed.

That which is claimed is: 1. Apparatus for formingvrigid web-reinforcedextruded composites comprising:

an extruder having an extrusion die conforming in shape to a pair ofsaid composites joined in mirror image relationship to each other, websupply means for feeding a pair of reinforcing webs into said die inspaced parallel relationship, supply means for feeding a curableelastomeric material into said extruder, a curing station positionedadjacent the output end of said die along the path of travel of the pairof extruded composites,

a slitting knife positioned along the path of travel at the point ofdivision between the pair of extruded composites to cut the elastomericmaterial and to separate the same into individual composites bycontinuous longitudinal splitting,

drive means engageable with the edge portions of said reinforcing websto draw said webs from the web supply means, through said extruder die,and past said slitting knife, and

cutting means positioned at the end of the path of travel of theextruded composite for periodically cutting both of said pair ofextruded composites to finished lengths wherein indexing notches areprovided along the peripheral edge of said reinforcing webs to activatesaid cutting means at desired intervals.

2. Apparatus as defined in claim 1 wherein said reinforcement web isperforated to allow strike-through of the extruded material in theextrusion die.

3. Apparatus as defined in claim I wherein said extruded composites arevehicle windshield wiper blades, said extrusion die conforms in shape toa pair of blades joined at the wiping edges thereof and said slittingknife forms the wiping edges of said blades.

4. Apparatus as defined in claim 3 wherein said reinforcing webs formthe backing members and attachments means for said windshield wiperblades.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT NO. U.S. 3,744,947

DATED July 10, 1973 INVENTOR(S) Max Skobel ltis certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

In column 1, line 7, "a method" should read the manufacture- In column4, lines 41 and 42, the word "attachments" should read attachment.

Signed and Scaled this Auest:

RENE D. TEGTMEYER Arresting Ofiicer Acn'lg Commissioner of Patents andTrademrks

1. Apparatus for forming rigid web-reinforced extruded compositescomprising: an extruder having an extrusion die conforming in shape to apair of said composites joined in mirror image relationship to eachother, web supply means for feeding a pair of reinforcing webs into saiddie in spaced parallel relationship, supply means for feeding a curableelastomeric material into said extruder, a curing station positionedadjacent the output end of said die along the path of travel of the pairof extruded composites, a slitting knife positioned along the path oftravel at the point of division between the pair of extruded compositesto cut the elastomeric material and to separate the same into individualcomposites by continuous longitudinal splitting, drive means engageablewith the edge portions of said reinforcing webs to draw said webs fromthe web supply means, through said extruder die, and past said slittingknife, and cutting means positioned at the end of the path of travel ofthe extruded composite for periodically cutting both of said pair ofextruded composites to finished lengths wherein indexing notches areprovided along the peripheral edge of said reinforcing webs to activatesaid cutting means at desired intervals.
 2. Apparatus as defined inclaim 1 wherein said reinforcement web is perforated to allowstrike-through of the extruded material in the extrusion die. 3.Apparatus as defined in claim 1 wherein said extruded composites arevehicle windshield wiper blades, said extrusion die conforms in shape toa pair of blades joined at the wiping edges thereof and said slittingknife forms the wiping edges of said blades.
 4. Apparatus as defined inclaim 3 wherein said reinforcing webs form the backing members andattachment means for said windshield wiper blades.